Though Marvin's name is not mentioned, a Shadow Monster Man appears in Petscop 6 accompanied by Toneth and spells out "WHERE IS MY HOUSE" "WHERE IS THE SCHOOL" and "I WILL FOLLOW"; this entity is then linked to the name "Marvin" in Petscop 7, where Pink Tool states "I LOVE YOU NEWMAKER PLEASE SHOW MARVIN WHERE HIS HOUSE IS".
Marvin finally shows up properly in Petscop 8, where Paul encounters a green figure who looks through screens as the windmill and house, and Paul remarks "this is Marvin, right?" and goes on to refer to him as "Marvin" several more times.
Marvin appears again in Petscop 11, barging in through an open window and knocking down an air conditioner to abduct Care, and later appears during the Demo Area sequence, where the player actively converses with Marvin through sequences of button presses.
In the demo area, Marvin appears what may be an office or classroom with a chalkboard and asks the player to "play music for baby she will become melody" and gives them the Needles Piano, at first praising their music as "Lovely" but later, after their notes sour, say "she tripped and fell and is lost" "Tiara plays bad music too" and tells the player to "Do it right next time", though after the player says "sad" he responds "OK pall".
Marvin appears briefly in Petscop 12, but does not say anything. At first glance, it would appear he is wandering aimlessly, but in truth, he is making the exact same movements as he did in Petscop 11, up until he reaches the school door, where he then stops in place. It is unknown whether or not these two events are occurring at the same time.
Marvin would make his next major appearance in Petscop 15, again inside the school. After instructing the player to sit at the front desk, he walks behind the chalkboard. After a long pause, a sound plays and Marvin comes out from behind the chalkboard with someone who he introduces as "Bell" due to the bell tone that plays when she talks. Marvin leaves, and "Bell" introduces herself properly as Tiara. She then asks the player to press "Nifty". Paul, confused about this, replies "Nifty". Tiara responds "No. Player One Press Nifty." Paul seemingly finds the "nifty" button, which allows him to draw on the walls of the school.
According to the message, Marvin is hurting whoever is speaking through pink Tool. From this we can conclude he is an evil man. If you believe in the Color Theory, you could say it’s Mike that’s being hurt by Marvin. The only other “character” we have been introduced to that seems to have evil tendencies is the man mentioned in the note in Care’s room. If this is true, then Marvin might also be the one responsible for Care’s downfall as well as other children.
The phrase “MARVIN PICKS UP TOOL” is still under discussion. It could be that Marvin is using Tool to hurt the child, or the “picking up tool” could be unrelated to how the child is being hurt. This message might also be referring to the smaller Tool-like objects found in Care and Mike’s bedrooms. As we are still unsure of the purpose of these objects, we can’t say for sure if they can be used to hurt someone.
The house was green when it was originally seen in a picture at 2:42 of Petscop 2. However, when Paul visits the house in Petscop 11 and subsequent episodes, the house is black. Since the color green is associated with Marvin, some theorize that this change in color signifies that Marvin no longer lives in the house when it is painted black. This is further reinforced by the text which says "The key works. It still works" at 5:17 in Petscop 11 when the player uses the key on the black house.
The fact that Marvin only hurts the child when the Playstation is on could indicate that the “people” in the game might not exist as long as the Playstation is off.
A recent theory was uncovered, that Marvin could be connected to real-life kidnapper and murderer, Marvin Gabrion, revealing more about Marvin's history.
Some theorist mention that Marvin's face looks like face in the supposedly late photo of nazi criminal Josef Mengele  which is also known as "angel of death ", and some conspiracy theories around project MK Ultra and Project Monarch mentions that he took sthe sole part in this projects as Dr.Green (thus the color of the face).
|Amber • Pen • Randice • Roneth • Toneth • Wavey|
|Care • Michael Hammond • Tiara/Belle|
|Green Man (Paul) • The Gift Plane Staff • "I" • Marvin • Mystery Man (Fan Name) • Newmaker • Quitter • Pyramid Head (fan name) • Shadow Monster Man • Tool • "You" (As Mentioned in Game) • Wife|
|Paul (Narrator) • "You" (As Mentioned by Narrator) • Rainer • Proprietors|